The present invention relates to a process for the production of rumen bypass feed supplements. The process converts glyceride oils to their respective fatty acid calcium salts. In particular, the present invention relates to a process for the production of calcium salts of unsaturated fatty acids derived from fish oil. The calcium salts of the present invention, when fed to cattle, provide reproductive benefits, in particular, an increase in fertility as embodied in an increased rate of impregnation. The present invention therefore also relates to methods for providing such benefits in a ruminant.
Dairy cows must be impregnated once a year to maintain a lactation cycle in which milk is produced for ten months at a time with two month rest periods in between during which the cow is dry. Given the gestation period of a dairy cow, the objective is to impregnate the cow within 83 days after calving. The efficient management of a dairy herd thus requires that the cows be maintained at the peak of fertility to ensure re-impregnation within 83 days.
Accordingly, there exists a need for nutritional supplements that promote dairy cow fertility. Fish oil fatty acids have become the focus of numerous research programs that seek to capitalize on their nutritional and physiological properties. WO 99/66877 discloses the use of omega-3 fatty acids of fish oil origin to increase fertility in animals including cattle. Among the omega-3 fatty acids disclosed are eicosapentaenoic acid (EPA) and decosahexaenoic acid (DHA).
Unsaturated fatty acids, however, undergo hydrogenation to saturated fatty acids by microbial action in the rumen and must be fed to ruminants in a protected form. The most familiar form in which fatty acids in general are protected from microbial action in the rumen are the fatty acid calcium salts disclosed by U.S. Pat. Nos. 4,642,317; 4,826,694, 4,853,233; 4,853,233 and 4,909,138. This form of fatty acid protection is widely accepted in the dairy industry.
Fish oils have a glyceride content of 100%. That is, all of the fatty acids in fish oils are in the glyceride form. Fatty acid glycerides do not readily react to form calcium salts using the processes disclosed by the above-listed patents. For a product to be commercially feasible, glyceride levels below about 5 weight percent are desirable to produce a free-flowing and stable product.
U.S. Pat. No. 5,382,678 discloses a process that reportedly can be used to prepare fatty acid calcium salts from feedstocks having glyceride contents as high as 40 weight percent, with the resulting product having a residual glyceride content of less than about 5 weight percent. Products with residual glyceride contents above 5 weight percent lack storage stability, and are susceptible to oxidation, post-heating, melting, subsequent product solidification, and a tendency to form lumps upon storage. Under industrial conditions, however, it has not been possible to consistently obtain residual glyceride levels below 5 weight percent once the initial glyceride content of the fatty acid feed stock is above about 25 weight percent when using the process of U.S. Pat. No. 5,382,678.
Hydrolyzing the glycerides to levels below 25 weight percent is not commercially feasible. Commercial omega-3 fatty acids in the free fatty acid form are so costly as to be commercially unfeasible. One can reduce the glyceride content of the fish oil starting material by blending it with a low glyceride content fatty acid feedstock, such as Palm Fatty Acid Distillate (PFAD), which has a glyceride content of about 15 to 20 weight percent.
However, the quantity of PFAD that would have to be added to fish oil to reduce the glyceride content to levels commercially feasible for use with the process of U.S. Pat. No. 5,382,678 dilutes the concentration of desirable omega-3 fatty acid such as EPA and DHA to ineffective levels. That is, the levels of DHA and EPA in the resulting calcium salt are so low that quantities of calcium salt must be added to the daily feed ration at levels above what is considered acceptable by the dairy industry.
To be commercially viable, omega-3 fatty acid calcium salt feed supplements must have DHA and EPA concentrations high enough to confer the beneficial effects of these omega-3 fatty acids when quantities of the calcium salt are added to feed ration at levels considered acceptable to the cattle industry. Therefore, a need exists for a process by which calcium salts may be prepared from fish oils having high concentrations of omega-3 fatty acid with the calcium salts produced with reduced levels of unreacted glycerides in a free-flowing and stable form easily handled by customers.